Vehicle brake



G. C. R. KUIPER VEHICLE BRAKE Oct. 29, 1940.

Filed May 9, 1936' 5 Sheets-Sheet l INVENTOR 65e/pep LEM/PEE ATTORNEY.

y 9, 195s s sneefs-snet z' G. C. R.VKUIPER VEHICLE BRAKE Filed Ma 66' y INVENTOR. 6fm/ea ce. fu/Ps3? ATTORNEY.

Oct. 29, 1940'.

' C. 29, '940. Q c, RJKU|PER 2,219,689

VEHICLE BRAKE Filed May 9, 193s 5 sheets-sheet s 205 zal 00 fg INVENTOR.

Tmc roe .5f-elche@ CE- ,Kw/PEE Oct. 29, 1940. G. c. R. KuuPER VEH I CLE BRAKE Filed May 9, 1935 5 Sheets-Sheet 5 VMM INVENTOR.

Z5/mep @E Kawa@ B ATTORNEY.

Patented Oct. 29, 1940 y UNITED STATES PATENT OFFICE VEHICLE BRAKE Application May s, l193e, serial No. 78,870

8 Claims.

This invention relates to new and useful improvements in vacuum operated brake mechanisms.

An object of the invention is to provide a highly sensitive reaction compensating type of control valve, which, under certain conditions automatically teeters between on and lapped positions to temper or modulate applications of the brake mechanism.

Another object of the invention is to provide a valve mechanism normally submerged in vacuum to maintain the valve in balanced position when in off position.

A further object of the invention is to provide a valve mechanism wherein during braking, one side of the valve is at all times subjected to vacuum and the other side to atmosphere thereby providing a differential pressure, which resists the efforts of the operator to apply the brakes, and "n the resistance varies substantially with the `differential pressure acting upon the valve to thereby enable the operator to gauge the extent to which the brakes are being applied.

Another object of the invention is to provide a hand control valve mechanism whereby the desired braking pressure may be applied to the brakes by manipulating a hand operated lever to positions representing different degrees of brake application.

Another object of the invention is to provide a brake system in which hydraulic brakes are initially actuated by power means, and subsequently by manual means.

Another object of the invention is to'provide a'` relay valve for combined tractor-trailer braking systems, for automatically applying the trailer brakes if the latter separates from the tractor,"

and seals the vacuum reservoir to thereby maintain the trailer brakesin brake applied position.

A further object of the invention is to provide auxiliary valve means to control the degree of tractor brake application without interfering with the operation of the trailer brakes to prevent so- (Cl. 18S-3) Fig. 1 is a sectional View of a foot control valve,

Fig. 2 is an end elevational view taken on line 2-2 of Fig. 1,

Fig. 3 is a sectional view of a hand control valve,

Fig. 4 is an elevational view of a portion of the hand control valve,

Fig. 5 is a perspective view of the cam means employed in the hand control valve,

Fig. 6 is a plan view of Fig. 3,

Fig, '7 is a sectional view of one form of relay valve,

Fig. 8 illustrates' a tractor-trailer brake hookup: I

relay valve,

Fig. 10 illustrates another formof tractor-trailer brake hook-up,

Fig. 11 is a horizontal sectional view partlyl in plan of another form of foot control-valve, and

Fig.12 is an elevational 4view illustrating an installation of the Valve shown in Fig. 11 for operating brakes either bypower or mechanically.

Referring now more particularly to Figs. l and 2, the numeral I designates a foot control valve composed of two valve housing sections I I and I2 secured together by screws I3. The section Il is provided with lateral ports I6, I1 and I8 communicating with an axially extending bore I4 terminating at its inner end in an enlarged chamber I5.` The port I6 communicates with the atmosphere through a breather or air cleaner I9, and the port I1 is adapted to communicate with a brake or power cylinder hereinafter describedl while the port I8 is adapted to be connected with the intake manifold of an internal combusition engine for its source of suction or partial vacuum.

Reciprocally mounted in the bore I4 is a piston l type Valve 20 having a reduced cylindrical end portion 2l to provide a recess 22 therebetween and the bore I4 which communicates with-the enlarged chamber I The valve '20.is further provided with spaced annular closure or rvalve members 23 and 24 which dene an annular recessed portion 25 of suilicient length to extend clear of the manifold port I8 and the brake cylindrical port I1 so that theports I1 and I8 are in communication with each other as shown in Fig. 1. A port 21 extends laterally through the piston valve 20 to provide communication between the end recess 22 and the I niddle recess 25. 'I'he outer end of the piston valve 20 has an axial cavity for the loose reception of an actuating stud or valve stem 29 which extends beyond the bore I4 and is pivotally connected at 30 to a foot pedal 3| fulcrumed on a rod 32 suitably supported on the Fig. 9 is a sectional View of another form of motor vehicle. A bearing member 33 suitably supports the valve stem 29 in the bore |4. A rubber boot 35 has one end seated in a groove around the valve casing section and the other end is disposed about the valve stem 29 to exclude extraneous matter from the bore I4.

A diaphragm 31 is rigidly secured to the inner extreme end of the piston valve 20 by means of a screw 38 and its marginal edge is secured between the housing sections -and I2 by means of the screws |3. 'I'he valve housing section |2 cooperates with the diaphragm 31 to form a diaphragm chamber 40. Relatively large washers 4| and 42 are arranged on opposite sides of the diaphragm 31, the washer 4| engaging an annular flange 43 at the end of the bore I 4 to limit movement of the diaphragm 31 and prevent damage to the same when the valve is in the position shown in Fig. 1. A conical spiral spring 45 surrounding the screw 38 seats at its small end against the washer 42 and the larger end of the spring is disposed in a seat 46 formed in the valve housing section I2, and one function of the spring 45 is'to normally urge the piston valve 20 to ofi position as shown in Fig. 1.

To communicate the diaphragm chamber 40 with the brake cylinder port i1, the valve housing section I2 is provided with an axial port 41 in which is suitably connected an end 48 of a conduit 49 which has its other end terminating in a bore 50 of a nipple 5| communicating With the brake cylinder port I1.

From the foregoing it Will be seen that the diaphragm chamber i5 communicates with a source of vacuum through the recess 22, lateral piston valve port 21, recess 25 and the Vacuum port I8, while the diaphragm chamber 40 is connected to the source of suction by means of the conduit 49, nipple port 50, brake cylinder port l1, recess 25 and Vacuum port i8. In other Words, the diaphragm 31 is submerged or balanced in vacuum when the piston valve 20 'is in neutral or off position which corresponds to brake release position. At the same time, air enters the bore I4 through the atmospheric port I6 at the rear end of the piston valve 20, so that atmospheric pressure is exerted on the latter which pressure is opposed and normally overcome by the conical spring 45.

This control valve may be employed in the vacuum suspended tractor brake system shown in Fig. 8 which comprises a vacuum suspended power actuatoror brake cylinder 200 closed at both ends and is provided with a piston 20| having a stem 202 adapted for connection with the brake rigging of the tractor. The rear end of the brake cylinder is connected to a'pipe 203 communicati ing with a manifold pipe 204 adapted for connection to the intake manifold of the internal combustion engine (not shown) of the tractor,A and the front end of the brake cylinder is connected to a conduit 205 leading to a pipe 206 connected with the brake cylinder port I1 of the control valve which has its manifold port I8 in open communication with a pipe 201 connected to the pipe 203 leading to the source of suction. It will be noted that the diaphragm 31 is submerged in vacuum and that the diaphragm chambers I5 and 40 are in communication with the front end of the brake cylinder when the tractor brakes are in released position.

When it is desired to apply the tractor brakes the operator depresses the foot pedal 3| causing the piston 20 to move against the tension of the spring 45, and the closure valve 24 ismoved past the brake cylinder port I1, whereby suction is cut oil to the latter and consequently to the front end of the'brake cylinder 260 and to 4the diaphragm chamber 40. This places the atmospheric port I6 in communication with the brake cylinder port I1 whereby air is admitted to the diaphragm chamber 40 through the conduit 49 subjecting the diaphragm 31 to a differential pressure, and the air is also admitted to the front end of the brake cylinder 200 subjecting the brake piston 20| to a differential pressure. The diierential pressure in the brake cylinder 200 causes the brake piston 20| to move toward the rear oi the brake cylinder to apply the brakes, While at the same time the differential pressure in the diaphragm chambers exerts a pressure against the diaphragm 31 which tends to move the piston 42|) to brake release position in opposition to the direction of force applied to the brake pedal by the operators foot. It will be noted that the differential pressure in the diaphragm chambers opposing the pedal pressure is caused by the air pressure in the diaphragm chamber 40 which is equal to the air pressure in the forward end of the brake cylinder 200, and by the fact that the diaphragm chamber i5 contains a vacuum at all times which tends to pull the diaphragm 31 in a direction opposite to the brake applying movement of the brake pedal. The diierential pressure in the diaphragm chambers tends to move the piston 20 to lap position upon slight retraction of the brake pedal 3|, and in lap position the closure valve 24 spans the brake cylinder port I1 to cut on the source of vacuum and atmosphere so that the brakes can be held in applied position as long as desired. As soon as the foot pressure is removed from the brake pedal 3|, the spring 45 moves the piston 20 from applied to release position, whereupon atmospheric air will be cut oi and the diaphragm chamber 40 and forward end 'of the brake cylinder 200 will again be connected to the manifold thereby permitting the brake piston 20| to be returned to normal position releasing the brakes, under the normal action of the usual brake retractor springs.

Figs. 3 through 6 disclose a hand control valve adapted to be employed in the tractor brake system shown in Fig. 8 and comprises a valve housing composed of sections 5| and 52 secured together by screws 53. The lower section 5| is provided with an axially extending bore having a reduced portion 55'terminating in an enlarged diaphragm chamber 56, and having an enlarged portion 51 closed by a removable plug 58. At the shoulder formed by the reduced portion 55 of the bore 54 is an annular recess in which is disposed a packing ring 59 having its inner peripheral surface in line with the surface of the reduced bore 55 and having a part of its flat rsurface displaced with respect to the enlarged bore 51. Extending laterally in the housing 5| and communicating with the axial bore 54 are ports 60, 6| and 62, the port 60 leading to the atmosphere through a breather or air cleaner 63, and the port 6| adapted to communicate with the conduit 205 leading to the brake cylinder 200 While the port 62 is adapted to be connected to the conduit 201 leading to the intake `manifold of an internal combustion engine for its source of suction or partial vacuum. The brake cylinder port 6| communicates with one end of a longitudinal passage 64 in the lower housing 5I and this passage communicates with the diaphragm chamber 56 to thereby at all times maintain the latter in communication with the front end of the brake cylinder 200.

Reciprocally mounted in the bore 54 is a piston type valve 65 provided at its outer end with an enlarged annular closure or valve 66 which intimately engages the enlarged bore 51, and is provided adjacent its opposite end with an annular closure or valve 61 which snugly engages the reduced bore 55. 'I'he annular closures 66 and 61 dene an annular recess 68 which at all times spans the atmospheric port 60 irrespective of the position of the piston valve 65. Disposed about the piston valve 65 is an inverted cupshaped packing 10 having its depending flange 1| extending toward the closure member 61 so that it will be distended into uid tight engagement with the reduced bore 55 by the atmosphere that might leak past the closure memberv 61. The

piston valve is normally held in oi position, as'

shown in Fig. 3, which represents release position of the hand control valve, by means of a spring 12 interposed between the piston valve 65 and the removable plug 58, the spring 12 also holds the closure member 66 in fluid tight relation end with lateral ports 15 at all times in communication with a diaphragm chamber 16 formed by a diaphragm 11 andthe upper valve housing 52. The diaphragm is rigidly secured to the piston valve 65 by a nut 18 and has its marginal edge clamped between the housing sections 5| and 52 by means of the screws 53. Washers 19 and are arranged on opposite sides of the diaphragm 11 to provide a bearing surface for the diaphragm 11, and the washer 19 secures the packing 10 to the piston valve 65.

In order to operate the piston valve 65 a valve actuating mechanism is disposed Within the upper chamber 16. Within this chamber is a sleeve 83, shown in detail'in Fig. 4, and has a stem 85 which rotatably extends through a central aperture 86 in the top 81 of the valve housing 52 and secured to the stem 85, by means of a screw 8 8, is an operating handle 90. The handle 90 is provided with a pointer I I2 movable over a series of indications on top of the housing 52 each of which represents a braking position of the control valve. A bracket I3 integral with the housing 52 facilitates mounting of the control valve to the dash board or steering column of the tractor. A transverse slot 92 is provided in the enlarged portion of the sleeve 83 for the slidable and rotatable reception of a cam pin 93 which engages the cam faces 94 of a cam 95 as shown in detail in Fig. 5.

Each of the cam faces is provided with a release pocket 96 in which the cam pin 93 rests when the valve is in released position, and a pocket 91 in which the cam pin 93 is locked when the valve is in fully applied position. The grade of each cam face 94 is relatively steep adjacent the release pockets 96 as shown at 98, so as to quickly move the valve mechanism to its initial operating position, the gra'de then becomes gradual as indicated at 99 whereby the valve is gradually moved to fully applied position. In order to prevent rotation of the cam the latter is provided with diametrically opposed slots |00 which fit over studs |0| depending integrally from the top Wall of the housing, and the slots |00 are of greater depth than the studs |0| to permit insertion of a suitable hook in the space therebetween for removal of the cam 95 from the housing 52.

Loosely disposed about the sleeve 83 is a cup shape spring retainer |05 provided with an annular iiange |06 upon which the cam pin 93 rests, and the spring cup |05 has an axial opening |01 in which is slidably mounted a pin |08 to whichis rigidly secured a disc |09. Interposed between the flange |06 and the disc |09 is a spring ||0 which holds the pin |08 in abutment against the extreme end of the piston valve 65 as shown in Fig. 3.

This hand control valve may be employed in the vacuum suspended tractor brake system illustrated in Fig. 8 and when so-embodied the front end of the brake cylinder 200 is connected to the manifold by means of the conduits 205 and 206, control valve ports 6| and 62 and conduits 201, 203 and 204. The diaphragm 11 is normally suspended in vacuum since the chamber 16 is at all times connected to the source of vacuum through the lateral ports 15, passage 1d, port 62 and conduits 201,203 and 206. And thelower chamber 56 is connected to the source of vacuum when the valve is in oif position by means of the passage 64, ports 6| and 62 and the conduits 201, 203 and 204.

To operate the control valve the hand lever 90 is rotated from oi position toward fully on position which rotates the cam sleeve 83 causing the cam pin 93 to move out of the release pockets 96 along the steep grade 98 of the cam surface. And since the cam pin 93 slides along the flange |06 of the spring cup |05, the latter is shifted relatively to the pin |08 to compress the spring ||0 whereby the pin |08 exerts Dressure against the piston 65 and overcomes the opposing force of the spring 18 to shift the piston 65 to a brake applied position corresponding to that indicated by the pointer ||2.

In this brake applied position the closure valve I 66 covers the vacuum port 62 and exposes the brake cylinder port 6|- so as to communicate with the atmosphere through port 60 and breathers 63. Consequently air is admitted to the front end of the brake cylinder 200 and since the rear end of the latter is in vacuum the piston 20| will be subjected to differential pressures and will move to the right, as viewed in Fig. 8,` to operate the tractor wheel brakes.

It should be noted'that when piston 65 is in brake applied position the diaphragm chamber 56 also communicates With.atmosphere through the passage 64, port 6|, recess 68 and port 60. so that the lower surface of the diaphragm 11 is subjected to atmospheric pressure at the same time that the front vend of the brake cylinder 200 is also subjected to atmospheric pressure. In other words, the pressure at the front of the brake cylinder 200 is subuum in chamber 16 and the air pressure in chamf -ber 56 combine to urge .the diaphragm 11 in an upward direction against the force of the spring ||0 and tends to shift the piston 65 to lap position without movement of the handle 90. And when the piston 65 is in lap position the closure member 66 spans the brake port opening 6| to 91 on the cam 95 and holds the handle 90 in this position.

Accordingly, it is seen that the operating handle 90 can be rotated to the desired braking position indicated on the dial to obtain the desired braking pressure at the tractor wheel brakes.

To release the brakes the handle 90 is shifted to off position whereby the springs 12 and ||0 together with the diierential pressure on diaphragm 11 operate to immediately move the piston 65 to oi or normal position. 3

'This hand control valve is also capable of controlling an air suspended brake cylinder, in which the brake piston is suspended in air, 'Without any change in the valve structure, it being only necessary to reverse the on and off positions with respect to the pointer ||2. When so modied that portion of conduit 203 between the pipe 201 and the rear of cylinder 200 is eliminated, the conduit 205 is disconnected from the front end of cylinder 200 and is connected to the rear end of cylinder 200, and the front end of the latter is exposed to atmosphere, and the piston 65, will, When in off position, uncover the brake cylinder port 6| to the breather 63 and the cam pin 93 will be locked in the pockets 91 to suspend the piston 20| in air. Upon operation the handle 90 will be rotated in the reverse direction and the piston 65 will move upwardly, as viewed in Fig. 3, to interrupt flow of air to the brake cylinder port 6| and uncover the manifold port 62 whereby the latter communicates with vthe rear end of the brake cylinder 200 to operate the tractor brakes.

The foregoing tractor brake system may be coupled to an air suspended trailer brake system shown in Fig. 8 as comprising a conduit 208 connected by coupling 209 to the pipe 206 of the tractor brake system and the opposite end of the conduit 208 is connected to a port |2| of a relay valve ||5 shown in Fig. '1 which has ports |21 and |28 respectively connected to conduits 209 and 2li), the latter communicating with the rear end of a brake cylinder 2|| the opposite end of which communicates with atmosphere. And reciprocally disposed in the brake cylinder 2|| is a piston 2|2 provided with a stem 2|3 adapted for connection with the brake mechanism of the trailer. A vacuum reservoir 2|4 located on the trailer has one end connected to the conduit 209 and the opposite end is joined to a conduit 2|5 coupled to the tractor pipe 2|6 by means of a coupling 2|1.

The.relay valve ||5 employed in this trailer brake system comprises a main valve housing formed in two sections ||6 and ||1 secured together upon the marginal edge of a diaphragm IIB-which divides the interior of the housing into two chambers ||9 and |20. The valve housing section ||6 is provided with the axial aperture |2| adapted to be connected to the conduit 208 l of the trailer `brake system whereby the chamber ||9 normally contains vacuum. Extending longitudinally of the valve section ||1 is a bore |22 having a reduced portion |23 and an enlarged portion |24, the reduced bore |22. terminates in the chamber |20 and the larger b'ore |24 is provided with a threaded sleeve |25 which is closed by a breather or air cleaner |26 communicating with the atmosphere. Lateral ports |21 and I 28 communicate with the bore |22, the port |21 being adapted for connection with the conduit 209 leading to the vacuum reservoir 2|4 and the port |28 is adapted to be connected to the conduit 2|0 leading to the rear end of the air suspended brake cylinder 2| Reciprocally mounted in the bore |22-is a piston type valve |30 provided with spaced annular closure members or valves |3| and |32 which define a recess |33 of sucient length to at all times span the vacuum -port |21. Extending transversely of the piston |30 is a passage |35 which at ll times provides communication between the vacuum port |21, and the chamber |20, whereby the latter contains vacuum irrespective of the position of the piston |30. One end of the piston |30 is secured to the diaphragm ||8 and is yieldably held in 01T position shown in Fig. '1 by a spring |31 interposed between the piston valve and the sleeve |25. The strength of the spring |31 is such that it will collapse when air is admitted to the chamber ||9 which causes the piston 30 to move from` oi to brake applied position.

Means have been provided to prevent leakage of air past the closure member |32 when the piston is in brake release or applied positions and comprises annular packing or sealing rings |40 and |4I. When the relay valve is in off position the closure member |32 engages the packing ring |40 to prevent leakage of air to the vacuum reservoir, and when the relay valve is in fully applied position the closure |32 is pressed against the sealing ring |4| to prevent leakage of air therepast to the vacuum reservoir and to the power actuator. In other Words, the piston valve |30 can be disposed in fully brake applied position without fear that the vacuum in the power cylinder will be dissipated and render the brakes useless.

To operate the relay valve the control valve, whether hand or foot operated, is moved to brake applying position and atmosphere is immediately admitted to the diaphragm chamber ||9. This creates a diierential pressure on the diaphragm I8, since the chamber |20 is at all times in communication with the source of vacuum, and accordingly the diaphragm ||8 and piston |30 is moved to the right as viewed in Fig. '7, to place the brake cylinder port |28 in communication With the manifold port |21 whereby the rear end of the bra-ke cylinder 2|| is exposed to vacuum which causes the piston 2|2 to move to the right as viewed in Fig. 8 and apply the trailer brakes. When the piston valve 30 is in brake applied position the annular closure |32 is disposed in sealing engagement with the packing ring |4| to prevent entrance of atmosphere from the breather |26, and consequently the degree of vacuum is not reduced.

In order to release the trailer brakes the opera.- tor controlled valve is moved to 01T position which interrupts the supply of air to the diaphragm chamber |9 and connects the latter to the source of vacuum, and the air entering the breather |26 moves the piston 30 to the position shown' in Fig. '1 in which position the the brake port |28 is exposed to atmosphere and connects the rear end of the brake cylinder 2|| with atmosphere to again suspend the brake piston 2|2 in air.

When the piston valve |30 is in oi position the closure member |32 engages the packing |40 in air tight relation to prevent loss of vacuum in the reservoir 214 or leakage of vacuum therepast to the brake cylinder 2|| whereby the atmos- --ing or:sealing.rings |12 and |13 `are disposed in pheric pressure therein isnot raried kand vthe 'brakes are not accidentally applied.

Should the Vtrailer accidentally separate from the tractor, air will be admitted into the trailer conduitl 208 and thence into the diaphragm chamber ||9 with consequent automatic brake application of the relay valve and of the trailer brakes, as will be understood. The trailer brakes are maintained in brake applied position for a considerable length of time after this accidental separatioxnbecause the packing |4| prevents entrance of atmosphere to the brake port |28 and to the vacuum reservoir 2|4 to thereby maintain the high degree of vacuum in the reservoir necessary to hold the trailer brakes in brake applied position.

Fig. ,9 relates to another form of relay valve which may be employed in the vacuum suspended trailer brake system illustrated in Fig. 10 and.

herein shown connected to a tractor brake system alike in all respects to the tractor brake system shown in Fig. 8. This vacuum suspended trailer brake system comprises a conduit 220 connected at one end to a port |5| of the relay valve shown in Fig. 9, which has a port |51 communicating through a conduit 22| with the forward end of a b rake cylinder 222 provided with a piston 223 connected to the brake rigging of the trailer. The rear end of the brake cylinder is connected to the reservoir 2 I 4 by means of a conduit 225 which also communicates through a conduit 226 with a bore |52 of the relay valve.

The relay valve herein employed? comprises a valve housing formed of two sections |46 and |41 secured together upon the marginal edge of a diaphragm |48 which divides the interior of the housing into two chambers 49 and |50. The chamber |49 is provided with the port |5| adapted to be connected to the conduit 220 whereby the chamber |49 normally contains a vacuum. The housing section |41 is provided with the axial bore |52 which is reduced at 53 and enlarged at |54, the reduced bore |53 terminates in the chamber |50 and the larger bore |54 has a threaded sleeve |55 adapted to be connected to the vacuum reservoir 2|4 and to the rear end of the brake cylinder 222 by means of the conduits 226 and 225. Lateral ports |56 and |51 terminate in the bore |52, and the port |56 is closed by a breather or air cleaner |56, while the port |51 is adapted to be connected to the -conduit 22| leading to the forward end of the brake cylinder 222.

Mounted reciprocally in the bore |52 is a piston type valve |60 secured to the diaphragm |48 which is held in the position shown in Fig. 9 by means of a spring |6|. Extending longitudinally of the piston is a bore |62 communicating at one end with the enlarged bore |56 and at the opposite end with lateral ports |63 at all times communicating with the chamber |50 so that the latter is always'in communication with the source of suction. Spaced about the piston |60 are annular closure or valve members |65 and |66 which denne therebetween a recess |61 at all times in communication with the atmospheric port |56.

In order to provide air tight seals with respect to the bore |52 and the piston |60, a cup-shape packing |10 is disposed about the piston |60 and has its annular depending flange |1| beveled and extending toward the atmospheric port |56 whereby air which might leak past the closure |65 will distend the iiange |1| into air tight engagement against the bore |53 and prevent pas sage of air to the chamber |50, Additional packthe bore |511, the sealing ring |12 being engaged by the closure member- |66 when the relay valve is in off position to prevent leakage of air to the brake cylinder .port A|5 1,1.anc l when the relay valve is in applied position the closure member |66 presses against the sealing or packing ring |13 to prevent leakage of air` to the vacuum port and thereby maintain the high degree of vacuum required to hold the trailer brake in appliedposition.

When the relay valve is in off position the diaphragm 48 is submerged'in vacuum and is held in the position shown in Fig. 9 by means of spring |6|. Upon moving the control valve tobrake applying position, air is immediately admitted to the diaphragm chamber |49 which subjects diaphragm |48 to a differential pressure and moves the latter and the piston |60 to the right as viewed in Fig. 9 to place the brake cylinder port |51 in communication with the breather |58 to thereby subject the forward end of the piston 233 to atmospheric pressure which causes the piston 222 to move to the right as viewed in Fig. l0 and apply the trailer brakes.

In order to release the trailer brakes the control valve is moved to the release position which again connects the diaphragm chamber |49 to the Source of suction through the control valve to balance diaphragm |48 in vacuum, and the brake cylinder port |51 is again in communication with the vacuum reservoir, whereby the brake cylinder piston 223 is suspended in vacuum.

Should the trailer separate from the tractor then the relay valve will automatically operate in the manner just described. And when in brake applied position the packing ring |13 prevents air from leaking therepast to the vacuum cylinder to thereby maintain the desired vacuum at the rear of the brake cylinder 222 to insure continued trailer brake application.

I have fo'ind that if a leak occurs in the tractor brake system and if at the same time the automobile engine cannot supply a degree of suction that will overcome the leak then the leaking air predominates over the suction and applies the tractor and trailer brakes without warning. This accidental braking occurs if the check'valves are maintained open solely by means of the vacuum in the brake system and when the degree of vacuum is low the check valves close automatically and accordingly the leaking air is'not absorbed by the automobile motor but accumulates in the brake conduits and eventually overcomes the suction in the nowclosed brake conduit and applies the brakes without warning.

In order to overcome this objectionable operation I have provided a check valve 230, herein shown, installed in the conduits 204 and 2|5, and is provided with a valve disc 23| normally held against a spider 232 in open position by means of a spring 233; If a leak'occurs in the tractor braking system the latter is at all times in communication with the automobile engine since the check valve 230 in the conduit 204 remains open and accordingly the leaking air is drawn off due to the suction provided by the automobile engine. The check valve in the conduit 2|5 also remains open and should the manifold suction fail to absorb ically closeddue to atmospheric pressure overcoming the pressure of the spring 233 whereby atmosphere is prevented from entering the reservoir 2 |4 and the trailer is not depleted of vacuum supply.

Referring to Figs. 8 and 10 the numeral 240 designates a metering valve of suitable construction which can be adapted to control the amount of air to be admitted to the forward end of the brake cylinder 200 when the control valve is operated. Under some conditions, upon operation of the control valve, the tractor brakes are applied prior to the actuation of the relay valve to operate the trailer brakes and this causes the so-called jackkning of the tractor trailer unit. That is the trailer has a tendency to telescope the tractor. I have found that by employing the metering valve 240 I can restrict passage of air through the conduit 205 and delay the operation of the brake cylinder 200 as desired, Without interfering with the usual operation of the relay.valve.

Figs. 11 and 12 illustrate a foot control valve for controlling a vacuum suspended power cylinder for actuating a hydraulic master brake cylinde'r, and lost motion means for manually operating the master cylinder in case the vacuum power fails or becomes deiicient. Numeral 250 indicates a vacuum suspended power cylinder having one end connected to 'a pipe 25| which is joined to a connector 252 communicating with a pipe 253 connected to the intake manifold of a motor vehicle. A pipe 254 connects the forward end of the power cylinder-250 with the brake port of a control valve 255 hereinafter described. In order to operate a trailer brake system, not shown, we have connected to the pipe 254 a conduit 256 leading to the trailer brakes. A piston 258 disposed in the power cylinder has a rod 259 connected to th-e lower end of a lever 260 fulcrumed as at 26| to a rod 262 carried on the motor vehicle. Intermediate the fulcrum .point 26| and the piston rod 259, the lever has pivotally connected thereto a plunger 263 of a hydraulic master cylinder 264 having a conduit system 265 not completely shown leading to the wheel brakes of the motor vehicle. The master cylinder 264 is carried by a bracket 266 secured to the rod 262.

The upper end of the lever 260 is pivotally connected to a rod 269 secured to a lost motion mechanism 210 comprising an elongated yoke 21| the arms 212 of which are provided with an elongated slot 213 to slidably receive a pin 214 which pivotally supports a pair of links 215 arranged to slide along the inner surface of the yoke arms 212 for a distance determined by the length of the slots 213. The forward ends of the links 215 are connected to a rod 216 pivotally connected at its forward end to a brake pedal 218 fulcrumed at 219. 'Ihe rear ends of the links 215 are pivoted to the upper end of a valve actuating lever 280 pivotally supported intermediate its ends by a pin 28| pivotally carried by the arms 212 of the yoke 21|. The lower end of the lever 280 is pivoted to a valve rod.282 loosely disposed in an axial port 283 of a plunger 284 forming part of the control valve 255.

The control valve shown in Fig. 11 comprises a housing made in two sections 29| and 292. The section 29| is provided with an axial bore 293 for the sliding reception of the plunger 284 about which is a packing 294 and a boot 295 to provide a substantially air tight seal therebetween. The housing section 292 and its Component parts are similar to the valve housing 6| and its enclosed structure as shown in Fig. 3 with the exception that the bore 51 communicates with the source of suction through the connector 252 instead of the manifold port 62 which may be closed by a removable plug. The breather 296 is shown herein mounted on the dash board of the motor vehicle and is connected by means of a conduit 291 to the atmospheric port 68 of the control valve. If desired the breather may be threaded directly to the valve housing.

In operation assume that the internal combustion engine is operating and creating a partial vacuum in the pipe line 253 it will be obvious that the power cylinder piston 258 will be submerged in vacuum since one side of the piston is exposed to vacuum by means of the connector 252 and pipe 25|, while the other side of the piston is exposed to vacuum through the connector 252, bore 51, brake port 6| and pipe 254. The diaphragm 11 is also submerged in vacuum, one side of the diaphragm communicating with the source of suction through the ports 15, passage 14, and bore 51, while the other side of the diaphragm is exposed through the passage 64, brake port 6| and bore 51. When it is desired to apply the brake, pressure is exerted on the brake pedal 218 causing the links 215 of the lost motion device to move relative to the yoke 21|, thereby moving the pin 214 longitudinally of the slots 213 and at the same time causing the valve operating lever 280 to swing on its fulcrum 28| against the tension of the valve spring 12 and move the plunger 284 so that the latter moves the diaphragm 11 and piston valve 65 to a position wherein the closure valve 66 is at the right of the brake port 6|, as viewed in Fig. 11, cutting ol the source of suction to the diaphragm chamber 56 and to the front end of the power cylinder 250. When the closure valve 66 is in this brake applied position atmosphere enters through the breather 296 to the annular recess 68 to the brake part 6| so that atmospheric pressure is created in the diaphragm chamber 56 and also at the left hand side of the piston 258 to cause the latter to move to the right. Creating. of atmospheric pressure in the diaphragm chamber 56 subjects diaphragm 11 to a differential pressure of vacuum on one side and atmosphere at the opposite side which resists the brake applying movement of the valve lever 280 and consequently the brake pedal 218 through the links 215 and rod 216. And since the diaphragm chamber 56 is in communication with the left side of the power cylinder 250 the opposing resistance exerted by the diaphragn11 against the pedal 218 will be a direct increment of the extent of atmospheric pressure existing at the left side of the piston 258, thereby accurately apprising the operator of the exact amount of power being exerted on the brake mechanism by the power actuator. Movement of piston 258 to the right causes the lever 269 to fulcrum at 26| and push the hydraulic piston 263 into the master cylinder 264 to distribute the hydraulic uid to the wheel brake cylinders and apply the brakes. This swinging movement of the lever 260 causes yoke 21| to move in the direction of the pedal and relative to the links 215 so that the control valve 255 will follow the pedal thereby restoring the lost motion connection to its original position. Upon release of pressure on the brake pedal the piston valve will be returned to normal position by the spring 12, and the piston 258 and diaphragm 11 will again be submerged in. vacuum.

Should differential pressures fail to be created in the power actuator 250 for any reason, continued movement of the pedal 2.18 in the direction of brake application will cause the pin 214 to bottom in the slots 213 after taking up the lost motion and thereby exert a direct pull from the brake pedal to the top of the lever 260 which will then fulcrum about 26| and force the hydraulic piston 263 into the master cylinder 264, whereby the pressure exerted on the hydraulic piston 263 is applied solely by the physical force of the operator.

It will be understood that various changes in the size, shape and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the appended claims.

vI claim:

1. In a power actuated brake system, a valve comprising a housing -having a high pressure port connected to a source of high pressure a low pressure port connected to avsource of low pressure and a brake port connected to a brake cylinder to operate the brakes, a diaphragm in said housing for lseparating said housing into two pressure chambersvalve means having a passage to at all times communicate one of said chambers with said low pressure port, said valve means being operable when in-one position to communicate said brake port with said low pressure port to automatically subject said vdiaphragm to the variable pressures in the brake cylinder, means 'for at all times communicating the other of said chambers with said brake port, and operating means for moving said valve means to another position to communicate said high pressure port with said brake port.

2. In a power actuated brake system, a valve comprising a housing having a high pressure port connected to a source of high pressure a low pressure port connected to a source of low pressure and a brake port connected to a brake cylinder for actuating the brakes, a plunger having spaced annular closures for controlling communication of said low pressure port and said high pressure port with respect to said brake port, said spaced closures dening a recess providing a passage between one of said pressure ports and said brake port, a diaphragm connected to said plunger, means dening a passage for exposing one side of said diaphragm to the pressure at the other of said pressure ports, and means defining a passage for exposing the other side of said'diaphragm to the pressure in said brake cylinder. y

3. In a power actuated brake system, a valve housing having a high pressure port connected to a source of high pressure a low pressure port cony nected to a source of low pressure and a brake port connected to a brake operating cylinder, a diaphragm in said housing for separating said housing into two chambers, Valve means connected to said diaphragm and having a passage to at all times communicate one of said chambers with said low pressure port, means for at all times communicating the other of said chambers with said brake port, said valve means when in one position establishing communication between said brake port and said low pressure port, hand controlled valve operating means including a spring acting on said diaphragm, and cam means for compressing said spring to move said diaphragm and valve meansto another position to connect said high pressure port with said brake port.

4. In a power actuated automobile brake, a valve housing having a high pressure port connected to the atmosphere a low pressure port connected to a source of low pressure and a brake port connected to a brake cylinder; a diaphragm in said housing for separating said housing into two chambers, a valve body means connected to said diaphragm and having a passage to at all times `communicate one of saidchambers with said low pressure port, said valve body when in one position establishing communication between said brake port and said low pressure port; means for at all times communicating the other of said chambers with said brake port; foot operated means for moving said valve body to another position to connect said atmospheric port with said brake port; and spring means disposed in said other chamber for acting on said diaphragm to oppose the pedal pressure.

5. In a vacuum brake system for motor vehicles including a tractor and trailer and having a source of suction, a power'actuator for each vehicle connected to said source of suction, a brake mechanism -onv each vehicle operated by its respective power actuator, a main control valve on the tractor, and an auxiliary valve on the trailer, conduit means connecting said source of suction with said auxiliary valve, a check valve housing disposed in said conduit means and providing an axial bore communicating with said conduit means, a valve disposed in said bore, and spring means for normally maintaining said valve unseated against the action of suction in said conduit means, said valve having such an area exposed to the fluid in said conduit means as to be operated by atmosphere entering said axial bore to eiect seating of said valve.

6. In a power actuated brake system, a valve housing having a bore, a valve plunger therein, said borehaving a high pressure port, a low pressure port and a brake cylinder port communicating therewith, said bore and housing terminating at one end .in an enlarged diaphragm compartment, a diaphragm in said compartment separating it into inner and outer chambers,

-means for securing the diaphragm to the end of said plunger, spring means for normally urging said plunger to a position causing said brake cylinder port to communicate with one of said other ports, means for at all times communicating one of said chambers with the low pressure port, means for at all times communicating the other chamber with said brake cylinder port, and said valve plunger being movable to alternately communicate the brake cylinder port with said other ports to apply and release the brake.

7. In a power actuated brake system, a valve comprising a housing having a bore, a valve plunger therein, said bore having a high pressure port, a low pressure port and a brake cylinder port, said bore and housing terminating at one end in an enlarged diaphragm compartment, a diaphragm in said compartment for separating it into inner and outer chambers, said valveplunger having a pair of reduced portions providing separated spaces communicated by a passage, one of said reduced portions of the valve plunger communicating with the inner diaphragm chamber, said valve plunger being operable when in one position to communicate said brake port with said low pressure port, means for at all times communicating the, other of said diaphragm chambers with said brake port, and .operating means for moving said valve means to another position to communicate said high pressure port with said brake port.

8. In a power actuated brake system, a val comprising a housing having a high pressure port connected to a source of high pressure, a low pressure port connected to a source of low pressure and a brake port connected to a brake cylinder for actuating the brakes, a plunger having spaced annular closures for controlling 10 communication of said low pressure port'l and 

